Oxygen-containing hierarchically porous carbon materials derived from wild jujube pit for high-performance supercapacitor

Hierarchically porous carbon (HPC) materials with rich oxygen-containing groups at the surface were prepared by a facile one-pot approach using wild jujube pit (WJP) as the biomass precursor. Effect of annealing temperature on the texture and electrochemical properties of the obtained HPC materials was investigated. After the WJP is annealed at 800 degrees C, the resulting HPC sample (WJC-800) contains 6.7% oxygen element and displays an ultra-high specific surface area (2438 m(2) g(-1)) and a high pore volume (1.00 cm(3) g(-1)). The WJC-800 sample possesses interconnected micro-, meso-and macro-pores, and such a structure is beneficial to enhance its electrochemical properties. In a three-electrode configuration, the WJC-800-derived electrode can deliver a specific capacitance of 398 F g(-1) (95.5 F cm(-3)) at 0.5 A g(-1), and retain 345 F g(-1) (82.8 F cm(-3)) (86.7% of that at 0.5 A g(-1)) even at 20 A g(-1). The capacitance retention of the assembled symmetric supercapacitor cell remains 97% and 87% in the 6 M KOH and 1 M Na2SO4 electrolyte after 10,000 cycles at 5 A g(-1), respectively. The symmetric supercapacitor cells using the 1 M Na2SO4 electrolyte attains a high energy density of 13.33 Wh kg(-1) at the power density of 16 kW kg(-1). The results indicate that the WJP can act as a novel and appropriate biomass precursor to prepare the low-cost HPC materials for high-performance supercapacitor. (C) 2017 Elsevier Ltd. All rights reserved.